It is known, e.g. from German utility model 77 10 873, to provide the end face of such a drill bit with three generally radially extending ridges that are angularly bent to form outer and inner cutting edges, the outer cutting edges converging forwardly toward the shaft axis while the inner cutting edges converge rearwardly toward same. The inner and outer cutting edges of each ridge meet in a forwardly projecting peak designed to trace a circle on the surface of a workpiece (e.g. of cast iron) approached by the relatively rotating drill bit, this circle being progressively deepened and widened into a V-groove serving to hold the tool centered. In order to facilitate the removal of chips cut out of that groove, not all inner cutting edges meet in a common point at the shaft axis; in fact, usually not more than one of these edges extends all the way to or possibly beyond that axis. However, all the outer cutting edges and all the inner cutting edges lie on two common conical surfaces centered on the axis, the peaks of all ridges being thus equidistant from the axis and located in a common transverse plane.
The handling of the chips--usually curled--cut from the workpiece by these frontal edges creates problems unless these chips are broken up into fragments. According to the teaching of the above-identified German utility model, this is accomplished by providing notches in the outer cutting edges. Since the flanks of the notches must be separately sharpened, this solution results in a rather complicated structure. Furthermore, since the notches necessarily lie rearwardly of the peaks in the axial direction, they do not come into play until the tool has penetrated the workpiece to a considerable depth.